linux-kernel - Re: [PATCH RFC v3 3/4] spmi: pmic-arb: Make core resources acquiring a version operation

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Message-ID: <CAA8EJpq=kYeZfNbFtfQ_oLS0Xi4imyEGV+dDNO+h6LZfqmpxZg@mail.gmail.com>
Date: Thu, 15 Feb 2024 11:30:23 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Abel Vesa <abel.vesa@...aro.org>
Cc: Konrad Dybcio <konrad.dybcio@...aro.org>, Stephen Boyd <sboyd@...nel.org>, 
	Matthias Brugger <matthias.bgg@...il.com>, Bjorn Andersson <andersson@...nel.org>, 
	Neil Armstrong <neil.armstrong@...aro.org>, 
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
	Srini Kandagatla <srinivas.kandagatla@...aro.org>, Johan Hovold <johan@...nel.org>, 
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-arm-msm@...r.kernel.org, linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH RFC v3 3/4] spmi: pmic-arb: Make core resources acquiring
 a version operation

On Wed, 14 Feb 2024 at 23:36, Abel Vesa <abel.vesa@...aro.org> wrote:
>
> On 24-02-14 22:18:33, Konrad Dybcio wrote:
> > On 14.02.2024 22:13, Abel Vesa wrote:
> > > Rather than setting up the core, obsrv and chnls in probe by using
> > > version specific conditionals, add a dedicated "get_core_resources"
> > > version specific op and move the acquiring in there.
> > >
> > > Signed-off-by: Abel Vesa <abel.vesa@...aro.org>
> > > ---
> > >  drivers/spmi/spmi-pmic-arb.c | 111 ++++++++++++++++++++++++++++++-------------
> > >  1 file changed, 78 insertions(+), 33 deletions(-)
> > >
> > > diff --git a/drivers/spmi/spmi-pmic-arb.c b/drivers/spmi/spmi-pmic-arb.c
> > > index 23939c0d225f..489556467a4c 100644
> > > --- a/drivers/spmi/spmi-pmic-arb.c
> > > +++ b/drivers/spmi/spmi-pmic-arb.c
> > > @@ -203,6 +203,7 @@ struct spmi_pmic_arb {
> > >   */
> > >  struct pmic_arb_ver_ops {
> > >     const char *ver_str;
> > > +   int (*get_core_resources)(struct platform_device *pdev, void __iomem *core);
> > >     int (*init_apid)(struct spmi_pmic_arb *pmic_arb, int index);
> > >     int (*ppid_to_apid)(struct spmi_pmic_arb *pmic_arb, u16 ppid);
> > >     /* spmi commands (read_cmd, write_cmd, cmd) functionality */
> > > @@ -956,6 +957,19 @@ static int pmic_arb_init_apid_min_max(struct spmi_pmic_arb *pmic_arb)
> > >     return 0;
> > >  }
> > >
> > > +static int pmic_arb_get_core_resources_v1(struct platform_device *pdev,
> > > +                                     void __iomem *core)
> > > +{
> > > +   struct spmi_pmic_arb *pmic_arb = platform_get_drvdata(pdev);
> > > +
> > > +   pmic_arb->wr_base = core;
> > > +   pmic_arb->rd_base = core;
> > > +
> > > +   pmic_arb->max_periphs = PMIC_ARB_MAX_PERIPHS;
> > > +
> > > +   return 0;
> > > +}
> > > +
> > >  static int pmic_arb_init_apid_v1(struct spmi_pmic_arb *pmic_arb, int index)
> > >  {
> > >     u32 *mapping_table;
> > > @@ -1063,6 +1077,41 @@ static u16 pmic_arb_find_apid(struct spmi_pmic_arb *pmic_arb, u16 ppid)
> > >     return apid;
> > >  }
> > >
> > > +static int pmic_arb_get_obsrvr_chnls_v2(struct platform_device *pdev)
> > > +{
> > > +   struct spmi_pmic_arb *pmic_arb = platform_get_drvdata(pdev);
> > > +   struct device *dev = &pdev->dev;
> > > +   struct resource *res;
> > > +
> > > +   res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
> >
> > It's no longer indented to deep, no need to keep such aggressive wrapping
> >
>
> The pmic_arb_get_obsrvr_chnls_v2 is used by both:
> pmic_arb_get_core_resources_v2
> pmic_arb_get_core_resources_v7
>
> > > +                                      "obsrvr");
> > > +   pmic_arb->rd_base = devm_ioremap(dev, res->start,
> > > +                                    resource_size(res));
> > > +   if (IS_ERR(pmic_arb->rd_base))
> > > +           return PTR_ERR(pmic_arb->rd_base);
> > > +
> > > +   res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
> > > +                                      "chnls");
> > > +   pmic_arb->wr_base = devm_ioremap(dev, res->start,
> > > +                                    resource_size(res));
> > > +   if (IS_ERR(pmic_arb->wr_base))
> > > +           return PTR_ERR(pmic_arb->wr_base);
> >
> > Could probably make it "devm_platform_get_and_ioremap_resource "
>
> The reason this needs to stay as is is because of reason explained by
> the following comment found in probe:
>
> /*
>  * Please don't replace this with devm_platform_ioremap_resource() or
>  * devm_ioremap_resource().  These both result in a call to
>  * devm_request_mem_region() which prevents multiple mappings of this
>  * register address range.  SoCs with PMIC arbiter v7 may define two
>  * arbiter devices, for the two physical SPMI interfaces, which  share
>  * some register address ranges (i.e. "core", "obsrvr", and "chnls").
>  * Ensure that both devices probe successfully by calling devm_ioremap()
>  * which does not result in a devm_request_mem_region() call.
>  */
>
> Even though, AFAICT, there is no platform that adds a second node for
> the second bus, currently, in mainline, we should probably allow the
> "legacy" approach to still work.

If there were no DT files which used two SPMI devices, I think we
should drop this comment and use existing helpers. We must keep
compatibility with the existing DTs, not with the _possible_ device
trees.

>
> >
> > Konrad



-- 
With best wishes
Dmitry